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Recently a friend of mine had a crown and pinion failure on his 90 TR. We took this opportunity to develop some replacement parts for all TR and boxer gearboxes since the gearsets and carriers interchange (other than final drive ratios on the 365's). My friend came up with a source to make custom gearsets in any ratio required that are a direct replacement for the original ones from ferrari. I came up with a billet steel differential carrier as a direct replacement for the original weak/welded original carrier along the lines of the 512M carrier but much stronger. Here are some shots of both the gears and the carriers I will be producing as an upgrade for anyone interested in improving the reliability of their TR or boxer gearboxes. The issue that concerns me the most is the welded on end cap that ferrari did on all boxers and TR's until the 512M came out. Ferrari saw the error of their ways and redesigned the carriers for the 512M to prevent breakage which usually damages the crown and pinion as well as the side gearbox supports. This failure is a very expensive occurrence and parts are usually NLA. The common upgrade was to buy a 512M carrier and away you go. Problem is cost and availability, NLA and expensive if you can find one. Not anymore, have a look.

The dark grey carrier is an original unit, the new ones are mine. The bolt on cap is to access the differential internals such as the posi clutches and the differential gears themselves. The opposite end was open when they machined the part then they simply welded a plate over the opening which held the support bearing. This is the flaw, the weld can and does break on some TR's and boxers with no warning. If this was to happen, the results are devastating not only to the gearbox but to your wallet as well. Ill be upgrading my boxer carrier when I do my engine out service as a measure of prevention, transfer the original ferrari internals and voila, no more worry in the back of my mind.

The gears are available in any ratio, Im considering changing my stock 3.21:1 ratio to something like a 3.73:1 which is closer to the 365 ratio for more out of the hole acceleration.
 

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